Saturday, May 24, 2014

Book Review: Inside the Human Genome: A Case for Non-Intelligent Design

I borrowed this slim (165 pages of text) book from the library thinking it would be easy reading about freaks of nature, tailbones, and other obvious disproofs of "intelligent" design. Nope, it is a very technical but fascinating discussion of the types of errors and detritus inside the actual ACTG sequences of actual human DNA. I have never taken a microbiology course, and I think that might have made this book easier reading, but I got through it thanks to high school biology, a college course on genetics, and keeping up with sciency books and magazines written for the layperson. Even so, I did have to renew it because it was rather slow-going. Despite the hard work, it was a real eye-opener for the detailed descriptions of various genetic processes.

There is a glossary and if you don't have much background in biology you will definitely need it. He does define most terms, but you have to remember them as they come up over and over. There is also quite a bit of alphabet soup. It's no wonder people with lower than average I.Q.s prefer the Bible's stories to actual science! But even if you have to go slowly, this book is worth the trip.

He begins with a brief history of the "problem of [natural] evil" and creationism as a movement.
The "eternal paradox" is the first chapter's title. This is the paradox of how or why a creator-god made so many diseased individuals if he was so perfect. The attempt to answer this quandary is called theodicy, and Avise traces its history a bit. He also talks about where natural selection fits in as a broad explanation:

It is also an unconscious and amoral artisan, totally devoid of intelligence, foresight, and ethics. From among the multitudinous genetic variants that arise in each generation via the now well-understood hereditary processes of mutation and recombination, natural selection in effect makes choices about which genes survive and proliferate to populate each new generations. (p.17)

FYI, that's one of his more readable sentences. Avise is a microbiologist at the University of California- Irvine (faculty bio page here) He knows his stuff! But he also knows the claims of Intelligent Design, and dispenses with their mischaracterization of natural selection (Michael Behe, a microbiologist & ID proponent, is his favorite target) in the first chapter:

Evolution does not equal unsophistication

Evolution does not equal random chance (though it is not devoid of chance/stochastic elements)

Natural selection does not ensure that only favorable genes establish

Complexity does not equal evolutionary improbability

Natural does not equal proper (ethical)

Evolution does not necessitate atheism*

*note, he makes many accommodationist statements in this book, but he does not seem to be a fan of religion.

The sequencing of the entire DNA genome of human beings led to a series of surprising discoveries, some of which explain where and how inherited diseases make their mischief within the genome. I was also very surprised by some of the findings of new genomic science. Each chapter after the first two discusses parts of the genome, and he lists diseases caused by malfunctions in each of them.

Chapter two has a lovely title: "Fallible Design: Protein-Coding DNA Sequences." He includes some history of biochemistry, which is a relief because he talks about people after Darwin who figured out the details, something authoritarian Christians seem to ignore (or are ignorant of). He also summarizes some of the concepts, and he is not writing for fourth-graders:

In the ensuing decades (after the Krebs cycle was discovered in 1937), biochemists gradually elucidated operational details in dozens of metabolic pathways within the bustling biochemical factories we call cells. These pathways interconvert, shuttle, or otherwise manipulate various organic molecules of diverse classes including lipids, proteins, vitamins and cofactors, simple and complex carbohydrates, and nucleic acids as well as constituent parts and secondary compounds from all of the above. (p44)

(I put the above quote into a reading level analyzer and it registered as 22nd grade, and that's just an average passage - there are some I had to read several times to grasp)

A few genetic disorders were the gateway to discoveries with broader significance, and he starts his discussion with some of them. One is Huntington disease, which is fatal. While discussing the research on this disease, Avise casually drops a small detail that made my jaw drop:

When human and mouse cells are mixed in a test tube, they often fuse spontaneously into hybrid cells that contain an initial full complement of chromosomes from both species. Through successive divisions of these hybrid cells, the human chromosomes tend to be lost more or less at random, sometimes until only one remains.

This little fact enabled a researcher named Nancy Wexler to identify the gene that causes Huntington's!

I was also astonished to see a diagram (p 57) of "the morbid anatomy of chromosome 2 in humans showing the mapped positions of genes underlying various inherited disorders." There are 22 of them, including red hair, colon cancer and obesity right next to rare and fatal diseases!

While I had hoped to find circus-worthy pictures in this book (there are no pictures), some of the diseases he describes painted mental pictures that were worth the read. My favorite is "maple syrup urine disease," which makes a person's urine smell like maple syrup! Another one I'd never heard of is Lesch-Nyhan syndrome, which causes children to compulsively vomit and hurt themselves. Another disorder makes people smell like rotten fish You can't make up this stuff!

The various parts of the genome were a big surprise to me too. "Junk DNA" includes sequences that came from viruses, which then replicated within the germ cells over countless generations. There are also genes that belong in the genome but over-reproduced, then became nonfunctional "pseudogenes" while the correct version continues to do its job.

I love this passage:

At face value, pseudogenes hardly seem like genomic features that would be designed by a wise engineer. Most of them lie scattered along chromosomes like useless molecular cadavers. This sentiment does not preclude the possibility that an occasional pseudogene is resuscitated asuch that it contributes positively to cellular operations; several instances are known or suspected in which a pseudogene formerly assumed to be genomic 'junk' was later deemed to have a functional role in cells... such (exceptions) hardly provide solid evidence for intelligent design; instead, they seem to point toward the kind of idiosyncratic genetic tinkering for which nonsentient evolutionary processes are notorious.

He stops short of calling them zombie genes, but I bet he knows we're thinking that!

The final category he describes had me floored: "mobile elements" or "jumping genes" are bits of DNA that replicate all over the genome, apparently without function or deleterious effects... most of the time. One category of these comprises 20% of the human genome, and the total is 44% ! These things may have come from retroviruses or bacteria, waaaaay back in our genetic history, meaning that 44% of the "human" genome is not human at all! These parasitical sequences are not just hanging out in the genome, though. Sometimes they help enabled mutations that drove natural selection and sometimes they help regulate genes.

Other times, they cause horrible diseases, such as specific types of hemophilia, breast cancer, colon cancer, neurofibromatosis, lymphoma, muscular dystrophy, and Tay-Sachs disease. It takes over two pages to list them (128-130).

One point that made me go "hmm" is that scientists have been able to correct defective genes in the laboratory, and this brings us back to the Problem of Evil and theodicy. If humans can fix defective genes, but God can't, what does that mean about God's omnipotence?

The final chapter takes on Behe directly, though if you have read the other chapters, it's impossible to buy any of the Intelligent Design ideas. Likewise, any theological explanation for allowing genetic disorders seems as silly as a talking snake or worldwide flood.

So after thoroughly explaining how genetics disproves any "intelligence" in the "design" of life, you'd expect him to point and laugh at religion. Unfortunately, in the end he claims that religion and science don't have to be enemies.

Despite his accommodationist leanings, I'd recommend the book for anyone wanting to know how (not why) things can go so badly wrong in our DNA.

Jerry Coyne's Why Evolution is True and Michael Shermer's Why Evolution Matters are also great books. If you haven't read them, I recommend reading them before tackling this one if you are leery of microbiology.